Sound recording apparatus



v May 26, 1931. I c, A HQXIE 1,807,409-

SOUND RECORDING APPARATUS Filed June 25, 1929 Inventor' Chau-Les A-Hox`Le, b5 Kiwa/277m HLS Attorneg.

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Patented May 26, 1931 UNITED vsitua-s PATENT oFFlcE i CHARLES n. noxIE, or ALrLAUs, NEW Yoan, AssIeNoa To GENERAL Enorme com- PANY, A CORPORATION or NEW Yom:

SOUND RECORDING APPARATUS 'Application led June 25, 1929. -'Seria1 No. 373,864.

My invention relates to apparatus for photographically recording sound on a film and an o ject of my invention is the provision of improved apparatus of this character 5 provided with means by which the film exposing light may be measured or compared with a reference light.

My invention will be better understood from the following description taken in connection with the accompanying drawin s, and its scope will be pointed out in t e appended claims. r. eferring to the drawings, Fig. 1 is a hori- 'zontal cross sectional view of an embodiment of my invention; Fig. 2 is a side elevation of the same drawn to smaller scale; Fig. 3 isI a view of the screen of variable transparency forming a part ofthe apparatus and Flg. 4 illustrates how the two light sources appear to the observer when viewed through the apparatus.

In the drawing, the casing 1 encloses the lm reels and the mechanism for moving the film at a uniform speed. This mechanism comprises in part the rotatable drum 2fwhich supports the film, not shown, at the point at which-it is exposed to the light beam. In the form of apparatus which I have illustrated,

a beam of light from the lamp 3 is vibrated by the oscillo raph mirror 4 in accordance with the sound waves to be recorded and by suitable optical means 5 is focused to a line of light on the film having a width of the order of one one-thousandth of an inch. The drum 2 is provided with the aperture 7 which will aline with the optical system 5 and is shown at the opposite side provided with the larger aperture 8. The drum has the end head 9 shown attached-thereto by small screws to which is secured the tube 10 havin one branch extending' toward the aperture and another branch extending toward the aperture 8. In each branch near its outer end is a-screen comprising a piece of ground glass 12 and adjacent it I have. Vshown another diifusing screen comprising a piece of opal glass 13. Mounted in the tube 10 at an an le of 45 and opposite aperture 7 is the mirror 16. 'Opposite the aperture 8 asecond mirror 17 is mountedin the tube- If the mirror 17 is a silvcred glass plate the silver simply ma be removed in the center to give the desired result. Attached to the cover 20 of the casin I have shown the tube 21 alining with t e tube 10 and having at the outer end the mirror 22 in front of the branch 23, On a suitable support 25 is the reference lamp 26 with which the exposing lamp 3 is to be compared. Bracket 27 attached to support 25 has the pivot pin 28 on which is rotatably mounted the circular screen 29. This screen as shown in Fig. 3 has a Avarying transparencythe variation occurring clrcumferentially so that when placed between the lamp 26 and the opening 8 the amount of light transmitted .into the drum may be varied by rotating the and the screen 29 should not change the color of the light coming from the reference lamp, thereby facilitating the comparison of the brightness of the two fields.

When a recordl is to be made the lamp 26 which is of standard power is irst illuminated andthe variable screen is adjusted to the point which has been found to be correct for the particular recording conditions prevailing, such as film sensitivity, length of development desired, etc., vor which may be indicated on a table of directions for using the apparatus. While the operator looks into the branch 2.3 of the tube 21 he varies the brilliancy of the exposing lamp 3 until the two areas 33 and 34I appear equally bright. Reference lamp 26 may then be turned off and the a drum adapted to support a sensitive film,

a recording lamp arranged to direct a light bea-m on sald film, said drum havin an opening therein through which said eam may pass, a tubular member within the drum having an observation opening, means for reflecting the light of said beam after passing through said opening through said tubular member, a reference lamp, and means in said tubular member for restricting the light observed from one of said lamps to a circular area and the light observed from the other lamp toa ring surrounding said circular area. 4

2. Sound recording ap aratus comprising a rotatable drum adapted to support a sensitive film, a recording-lamp, means for focusin light therefrom into a narrow beam on a lm on said drum, a tubular member arranged in the drum axially thereof, said drum having an opening through which said beam may pass, a mirror in the tubular member for reflecting said beam longitudinally thereof, a reference lamp, and a second mirror in said tubular member arranged in the path of the light from both of said lamps and having means to provide two adjacent fields' illuminated by light respectively from said reference lamp and from said narrow beam.

3. In a sound recording ap aratus having alfilm supporting drum providied withv a light openlng, a recording lam arranged to direct a light beam on sai drum, a second lamp, a photometric device arranged in said rum and comprisin a mirror for reflecting light received throug said opening from said recording lamp, a mirror arranged adjacent the reflected light from said first mirror for refiectlng light from said second lamp, and a rotatable `screen having circumferentially variable transparency arranged in the path of light from said second lamp.

ror in the tube arranged to refiect longitudinally of the tube a light beam from said lamp whereby the two refiected light beams may be compared.

5. A sound recordingapparatus comprising a rotatable drum adapted to support a film and having a light opening therein, means for directing a sound controlled light beam toward the drum, a reference lamp mounted exteriorily of the drum, and a photometric device mounted in the drum comprising a tube extending axially of the drum, a mirror therein arranged to receive light through said opening and reflect it longitudinally of the tube, a second mirror having a transparent central portion arranged in the pathof light reflected from said first mirror for reflecting light from said lamp, and a rotatable screen having circumferentially varying transparency arranged in the path of light from said lamp.

In witness whereof, I have ereunto set my hand this 24th day of June, 1929.

CHARLES A. 'HOXIE 4. A sound recording apparatus comprivsing a rotatable drum adapted to sup ort a film and having a light opening tl? means for directmg a sound controlled light beam toward the drum`,'\a reference 'lamp erein,

mounted exteriorily of the drum and a photov n metric device mounted in the'drum compris- 4 ing a tube extending axially of the drum, a mirror therein arranged to receive light through said opening and to reflect it 1ongitudmally of the' tube, and a second mir 

